Pallet for moving and securing cargo

ABSTRACT

A pallet to support cargo items for movement over ball mats and roller trays is relatively thin and of light weight and of sufficient resilient flexibility to bend and bow out of its plane to accommodate itself to relatively high points of a supporting structure without permanent deformation. The invention teaches new constructions of pallet sockets for engagement by cargo anchoring fittings. Some forms of the pallet are reversible for use with either of its faces uppermost.

United States Patent Looker [54] PALLET FOR MOVING AND SECURING CARGO[72] Inventor: Robert Looker, Santa Monica, Calif.

[73] Assignee: Satco Inc., El Segundo, Calif.

[22] Filed: Jan. 22, 1970 [21] Appl. No.: 4,882

[52] U.S. Cl ..248/346, 108/55, 248/361 R [51] Int. Cl. ..B65d 19/38[58] Field of Search.248/36l R, 361 A, 346; 108/57,

[451 Oct. 17,1972.

3,422,508 1/1969 I-liguchi ..248/361 X 3,428,002 2/1969 Mclntire..108/57 3,429,536 2/1969 Petry ..248/346 3,452,958 7/1969 Hambleton..248/361 3,509,832 5/1970 Daisley ..108/51 FOREIGN PATENTS ORAPPLICATIONS 522,589 6/1940 Great Britain ..52/624 PrimaryExaminer-Chance11or E. Harris Attorney-Smyth, Roston & Pavitt [57]ABSTRACT A pallet to support cargo items for movement over ball mats androller trays is relatively thin and of light weight and of sufficientresilient flexibility to bend and I bow out of its plane to accommodateitself to relatively high points of a supporting structure withoutpermanent deformation, The invention teaches new constructions of palletsockets for engagement by cargo anchoring fittings. Some forms of thepallet are reversible for use with either of its faces uppermost.

13 Claims, 39 Drawing Figures V mg\\\\\\\\\\\Z\\\\\\\\\\\\\\ 7PATENTEDnm 17 1972 3.698.677

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PALLET FOR MOVING AND SECURING CARGO BACKGROUND OF THE INVENTION Thisinvention relates to a base structure to serve as a pallet or to serveas the bottom of a container for moving cargo into and out of the cargospace of a vehicle such as an aircraft and may be either in the form of-a flat pallet for anchorage of cargo thereto of a flat base or a cargocontainer.

It is common practice to provide a cargo space with rotatable elementsin the form of balls or in the form of rollers to define a support planeand to facilitate movement of cargo items along the support plane. Forexample, the Davidson U.S. Pat. No. 3,262,588 discloses a structure forthe floor area of a cargo space of an air craftwherein ball mats definean entrance area opposite the side door of the cargo space of anaircraft and rollers are incorporated in so-called roller trays thatextend longitudinally of the aircraft in both directions from theentrance area. The balls of the ball mats are universely rotatable abouttheir centers to define a support plane along which palletized orcontainerized cargo may be moved in all directions with minimumfrictional resistance and the rollers of the roller trays are freelyrotatable to define support planes along which cargo may be moved withminimum frictional resistance.

The heretofore prevalent type of pallet or container base for movingcargo into and out of such a cargo space comprises a relatively rigidlaminated panel which may be of a thickness of three-fourths inch and isusually 88 inches wide and 125 inches in length. One common panel ofthis type is of high pressure laminated plywood construction bonded withthe melamine with top and bottom phenolic high pressure laminate skinsof approximately one-tenth inch thickness. Another such panel ofsandwich construction bonded with epoxy or phenolic resin has an endgrain balsa wood core with top and bottom skins of aluminum alloy of athickness of approximately one-sixteenth inch. Laminated panels of thesetypes have a weight in the range of 200 250 pounds and may costapproximately $360.00 each.

Unfortunately, such a conventional panel of this type usually has aservice life of only one to two years and only rarely under idealconditions may have a service life as long as 2 or 3 years. Not only isthe first cost high and the service life relatively short, but alsothere is the disadvantage of high maintenance cost. Daily inspectionsfor air worthiness are in order and if a pallet is found to be damagedit is not easily repaired. Damaged pallets must be transported to arepair location with consequent transportation costs as well as loss ofthe service of the pallet during the repair period.

One cause of damage to a conventional pallet is impacts by falling cargoitems. If a heavy cargo item is dropped on a pallet at a point where thepallet is supported from below by an unyielding structure, the pallet issubjected to a severe blow across its thickness that results in at leasta permanent dent or fracture in one or both of its skins. If the pointof impact by a falling cargo item is between two underlying spacedsupports, for example, spaced rollers of a roller tray, the palletstructure is subjected to concentrated high magnitude bending stress ina small area. Since the pallet structure is not resilient it is notcapable of dissipating the energy and the result is local damage theskin being displaced inwardly and thus dented if not cut, and the coreof the panel often delaminating from the skin. Another cause of damageoccurs when a heavily loaded panel is moved over an uneven supportsurface, for example a support surface having a high point extendingabove the normal support plane. Such a high point may be an upwardlydisplaced roller or ball element protruding above the surroundingsupport plane and is often a broken rotary element. Since the pallet isinherently relatively rigid the result is high unit loading at the highpoint, the load that is carried by a large area of the panel beingconcentrated at the high point. The greater the rigidity of the panelthe higher the stresses imposed on the bottom skin and the consequentgreater likelihood of deformation and or rupture of the skin.

Another cause of damage to ,a conventional pallet is found in thestresses involved in transferring a loaded pallet from one support planeto an adjacent support plane at a lower level. The transition of theloaded pallet from the higher plane to the lower subjects the pallet tosevere bending stresses that tend to deform the aluminum skin balsa woodcore with a permanent set. While being conveyed over irregular conveyingsurfaces the bottom skin deforms into small grooves as the pallet isconveyed over the projections. After having been so conveyed many timesthe bottom skin grooves take on the appearance of irregularcorrugations. When such pallet is then conveyed from a higher to a lowerconveying surface bending stresses are induced into the panel puttingthe top skin in compression and the bottom skin in tension. The tensilestresses induced upon the bottom skin cause the grooves or corrugationsto straighten effectively lengthening the bottom skin and causing thepallet to take a concave bowed shape, often in magnitude such as to keepthe pallet from fitting under the fixed height floor locks in thevehicle.

Additionally, if there is local delamination of the skin from the core,such delamination spreads easily to adjoining areas from the stressesinduced on both top and bottom skins as the pallet is conveyed from ahigher conveying surface to a lower conveying surface. After arelatively short service period the panel usually becomes bowed anddelaminated in small areas with the under surface badly cracked and withthe top surface caved in at various points.

The object of the present invention is not only to circumvent thesevarious causes for the shortened service life of a panel but also toprovide a panel of substantially less first cost and substantially lessweight as well as to substantially eliminate maintenance costs.

SUMMARY OF THE INVENTION One reason for the described construction of aconventional panel is that the panel is intended to be sufficientlyrigid to carry a heavy cargo when the panel is carried by a lift fork.It has also been assumed heretofore that a panel must be of relativelyheavy and rigid construction to cooperate with cargo captivating meanssuch as a cargo net. A conventional cargo net has a number of strongDacron or Nylon webs running in the fore and aft direction and in acrash condition the cargo net is exceedingly highly stressed. Totransmit this stress to the floor structure of the aircraft, T- shapedlocking devices are commonly used which overhang marginal portions of apanel and in certain cargo systems have arms that pass through rings onthe ends of the webs of a cargo net;

The present invention arises from a newly arrived conclusion that makingthe pallet sufficiently rigid for cooperation with a lift fork and alsomaking the pallet of heavy enough construction to carry peak crash loadsis actually wasteful and substantial savings may be made by designingsuch a pallet primarily for moving cargo items into and out of the cargospace of an aircraft and for effective anchorage in the aircraft.Carrying out this concept sacrifices the capability of the pallet tocarry a load on a lift fork but only moderately reduces the capabilityof the pallet for carrying peak crash loads. What is given up turns outto be a small price for the surprising economies achieved by extendingthe service life of a pallet as well as by drastically reducing the costof maintenance of the pallet.

The pallet construction taught by the present invention comprisesessentially a rectangular panel that is relatively thin and isresiliently flexible but, nevertheless, when anchored to the floor of anaircraft by conventional locks has sufficient strength and rigidity toretain the cargo thereon under normal accelerations and decelerationseven including survivable crashes. In some embodiments of the invention,the pallet is thickened along its four sides to, in effect, incorporatea rectangular protecting and reinforcing frame that is capable oftransmitting stresses of substantial magnitude across the panel. Evenwhen the panel incorporates such a reinforcement frame, the majorportion of the area of the panel is flexible where flexibility isrequired for the panel to accommodate itself to any support structure onwhich it may be placed. Severe unit stressing by a high point of theunderlying support structure is avoided by the capability of the panelto flex at the high point and thus accommodate itself to theirregularities of the support structure by distributing a substantialportion of the load to adjacent regions of the support structure.

If falling cargo makes a severe impact at a point 7 where the thin panelis rigidly supported from below, the thin solid sheet material of thepanel is capable of withstanding the impact force across its thicknesswith only insignificant deformation. If the impact of falling cargooccurs between points where the thin panel is supported from below, theexample midway between two underlying rollers, the panel tends merely toflexresiliently to absorb the load without permanent deformation or set.

If the panel is used to move a load across a juncture between twosupport structures with an abrupt change in level at the juncture, thepanel assumes a curved configuration for transition from one plane tothe other without being flexed beyond its elastic limit. The thickenedrectangular frame portion is a compromise between the high degree offlexibility required in the central area of the panel and the higherstrength required at the marginal regions of the panel, the compromisepermitting the frame portion to bend liberally without taking apermanent set.

The whole panel may be made of metal such as aluminum alloy or ofequivalent material such as plastic reinforced by embedded glass fibersand may be a onepiece body. The weight of the panel is minimized eitherby making the major central portion of the panel thinner than themargins of the panel or by recessing the material in the major centralarea without reducing the overall thickness in the central area. In bothcases the major central portion of the panel has a ratio of mass to unitplan area substantially lower than the ratio of mass to unit plan areaof the marginal portions of the panel around its four sides.

Some embodiments of the invention have the impo'rtant feature of beingreversible for use with either face of the panel uppermost. inevitablysome of the downward impacts to which a panel of the invention issubjected deforms the panel out of its normal plane. It has been found,however, that reversing a battered panel of the new construction resultsin subsequent downward impacts to restore the configuration of thepanel. Thus a reversible panel will outlast a non-reversible panel.

With reference to the sockets in a panel for engagement bycargo-retaining fittings, one embodiment of the invention employs asocket in the form of a sheet metal stamping that is riveted to thepanel so that the panel is not locally weakened by the socket. Otherembodiments of the invention have sockets in the form of recesses in thepanel material and still others have sockets in the form of apertures inthe panel material. The recesses and apertures may be reinforced bymetal plates to avoid locally weakening of the panel or even to addlocal strength to the panel. The invention also teaches that areversible panel may be provided with sockets for use with either faceof the panel uppermost.

- The features and advantages of the invention may be understood fromthe following detailed description and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, which are to beregarded as merely illustrative:

FIG. I is a fragmentary plan view of one embodiment of the invention inwhich the central area is perforated without reduction in thickness;

FIG. 2 is an enlarged fragmentary section along the line 2 Q 2 ofFIG. 1;

FIG. 3 is a view similar to FIG. 1 showing a panel which has blind boresin its central area;

FIG. 4 is an enlarged fragmentary section along the line 4 4 of FIG. 3;

FIG. 5 is a view similar to FIG. 1 showing a panel which is lightened inits central area by numerous recesses;

FIG. 6 is an enlarged fragmentary cross section along the line 6 6 ofFIG. 5;

FIG. 7 is a view similar to FIG. 1 illustrating a panel that islightened by internal voids in its central area;

FIG. 8 is an enlarged transverse section along the lines 8 8 of FIG. 7;

FIG. 9 is an enlarged section along the line 9 9 of FIG. 8;

FIG. 10 is a fragmentary plan view of a panel which comprises simply asheet of uniform thickness made of aluminum or of reinforced plasticmaterial;

FIG. 11 is a plan view of a panel having a frame portion along its foursides surrounding a thinner major central portion;

FIG. 12 is an enlarged fragmentary section taken along the line 12 l2ofFIG. ll;

FIG. 13 is a sectional view similar to FIG. 12 illustrating anotherembodiment of the invention;

FIGS. 14, 15 and 16 are views similar to FIGS. 12

and 13 illustrating additional embodiments of the invention;

FIG. 17 is a plan view of a fragment of a panel showing how the panelmay be reinforced at each of its four corners;

FIG. 18 is an enlarged section along the line 18 18 of FIG. 17;

FIG. 19 is a viewsimilar to FIG. 18 illustrating another form of cornerreinforcement;

FIG. 20 is a plan view of a socket of the panel in the form of anaperture through the panel with the aperture reinforced by a pair ofmetal plates;

FIG. 21 is a sectional view along the angular line 21 21 ofFlG. 20;

FIGS. 22, 23 and 24 are views similar to FIG. 21 illustrating otherforms of a reinforced panel socket;

FIG. 25 is a fragmentary plan view of a socket in the form of anaperture through the material of a panel;

FIG. 26 is a transverse section along the line 26 26 of FIG. 25;

FIG. 27 is a plan view of a portion of a reversible panel having twosets of sockets therein for use respectively at the two faces of thepanel;

FIG. 28 is a section along the line 28 28 of FIG. 27;

FIG. '29 is a section along the line 29 29 of FIG. 27;

FIG. 30 is a fragmentary plan view of a panel showing another form ofsockets for use with either face of the panel uppermost;

FIG. 31 is a section along the line 31 31 of FIG.

' FIG. 32 is a section along the line 32 32 of FIG. 30; FIG. 33 is aplan view of a socket that is in the form of a sheet metal stamping thatis attached to the panel;

FIG. 34 is a section along the angular line 34 34 of FIG. 33;

FIG. 35 is a plan view of still another embodiment of a panel;

FIG. 36 is an enlarged fragment of FIGS. 35;

FIG. 37 is a fragmentary section taken along the line 37 37 ofFIG. 35;

FIG. 38 is a fragmentary section taken along the line 38 38 ofFlG. 35;and

FIG. 39 is a section similar to FIG. 37 showing a modification of thepanel.

DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION In theembodiment of the invention illustrated by FIGS. 1 and 2, the panel,which may, for example be 88 inches wide and 125 inches long, isessentially a plate of suitable material of uniform thickness with asolid marginal portion 40 along its four sides surrounding a majorcentral area that is reduced in weight by numerous apertures orperforations in the form of bores 42. The panel may be made of anysuitable material, for example an aluminum alloy or a suitable plasticmaterial, which plastic material may be reinforced by embedded glassfibers. The purpose of perforating the large central area is to reducethe weight of the central area by reducing the ratio of the mass to unitplan area of the central portion below the ratio of mass to unit planarea of the marginal portion 40. The advantage of perforating the panelfor this purpose is that the perforations reduce the mass and,therefore, the weight of the large central area without correspondinglyreducing the resistance of the panel to flexure. Thus an aluminum panelof this construction may" be relatively thin, for example of athickness'in the range of 0.150 inch 0.375 inch to strike a desirablecompromise between rigidityand flexibility without undue sacrifice offlexibility in the major central area.

The panel shown in FIG. 3 is a similar plate of suitable material havinga solid marginal portion 44 along its four sides but in this instancethe major central area of the plate is provided with numerous blind.bores 45 which extend into the plate from opposite faces of the plate.The blind bores serve the same purpose as the perforations 42 in FIG. 1.

FIGS. 5 and 6 illustrate an embodiment of the invention in which thepanel is a similar plate of a selected thickness. The panel has a solidmarginal portion 46 along its four sides with the ratio of mass to unitsurface area of the major central portion of the plate reduced bynumerous shallow recesses 48 in the opposite faces of the plate.

It is to be noted that the panels shown in FIGS. 1 6 are of one-piececonstruction and therefore may be aptly termed monolithic panels.

FIGS. 7, 8 and 9 show the construction of a panel having a solidmarginal portion 50 extending along its four sides with the majorcentral area of the panel reduced in weight by voids inside the materialof the panel. In the construction shown the panel comprises two bondedor welded or otherwise attached laminations 52 and 54 of aluminum orother suitable material with recesses or grooves in one of thelaminations at the inner face between the two laminations to provide thevoids for reducing the ratio of mass to unit plan area. FIG. 8 showsparallel grooves 55 in the inner face of the lamination 52 and FIG. 9shows similar parallel grooves 55 in the inner surface of the lamination54, the two sets of grooves being perpendicular to eachother to providea pattern of intersecting voids that is indicated by broken lines inFIG. 7.

FIG. 10 shows how a panel to serve the purpose of the invention maycomprise simply a single plate 56 of suitable material such as aluminumor reinforced plastic, the ratio of mass to unit plan area being uniformover the whole plate.

FIGS. 11 and 12 show a panel in the form of a single plate of aluminumor plastic having a solid marginal portion 58 of selected thicknesssurrounding a large central portion 60 of substantially less thickness.Thus the marginal portion 58 is the equivalent of a rectangular frame ofsuitable thickness and the central portion 60 is a web of material ofsubstantially lesser thickness. As shown in FIG. 12 the frame ormarginal portion 58 is integral with the central portion 60, the panelbeing a single body of material. It is to be noted that a panel of thecross-sectional configuration indicated in FIG. 12 is symmetrical withrespect to its central plane.

FIG. 13 shows how a panel similar to FIG. 11 may comprise a rectangularframe 62 united with the four sides of a thinner plate or sheet 64. Itis contemplated that the frame 62 will be fabricated by interconnectingfour frame members at the four corners respectively of the panel. Asindicated in FIG. 13, each of the four panel members may be formed witha slot 65 opening onto its inner edge to straddle the corresponding edgeof the central sheet 64, the frame member being ridigly attached to thecentral sheet by suitable rivets 66.

It is to be noted that the cross-sectional configuration in FIG. 13 isalso symmetrical with respect to a central area. The symmetricalconfiguration is especially advantageous in a panel in which the frameis made of separate members because when the panel is flexed out of itsplane, the resulting stresses tend to separate the rectangular frame 62from the sheet 64, this tendency being minimized when the centroid ofthe frame and the sheet coincide.

FIG. I4 shows a panel which is similar in construction to the panelshown in FIG. 12 but is not symmetrical in cross-sectionalconfiguration. The panel in FIG. 14 is a single sheet of material havinga rectangular frame portion 68 surrounding a central thinner web 70.FIG. shows a panel of substantially the same crosssectionalconfiguration as the panel in FIG. 13 but in this instance therectangular frame 72 is joined to a central sheet 74 by suitable rivets77. It is to be noted that the frame 72 has a V-shaped groove 75 andthat the edge 76 of the sheet 74 is bevelled to fit snugly into thegroove. By virtue of this construction the edge 76 of the sheet ispositively interlocked with the frame 72.

Since the panels shown in FIGS. 12 and 14 are of one-piece constructionthey also may be aptly termed monolithic panels.

FIG. 16 illustrates a panel of cross-sectional configuration similar tothe crosssectional configuration of FIG. 15. Here again the frame 78 ofthe panel is separate from a sheet 80 that forms the central portion ofthe panel and here again the frame overlaps the sheet and is attachedthereto by suitable rivets 82.

FIGS. 17 and 18 show how a separate frame 84 of a panel such as shown inFIGS. 13, 15 and 16 that is connected to a central sheet 85 by suitablerivets 86 may comprise four frame members 84a which are mitered to meetat diagonal junctures 88. The adjoining ends of the panel members areinterlocked by arcuate corner reinforcements 90 which preferably aremade of relatively hard and tough material such as steel. As shown inFIG. 18 each corner reinforcement 90 may be formed with a slot 91 topermit the corner reinforcement to straddle a reduced edge portion ofthe confronting panel members 84a, the reinforcement being secured tothe confronting panel by suitable rivets 92.

FIG. 19 shows how a similar corner reinforcement 90a may be formed witha flange 94 of reduced thickness that is straddled by the confrontingframe members 84a, the corner reinforcement being secured by suitablerivets 92a.

The various described panels may be provided with any of the followingsocket constructions shown in FIGS. 20 34. In this regard a feature ofthe invention is the concept of providing a reversible panel which maybe used with either of its faces uppermost and which is equipped withsockets accessible at both of its faces for engagement withcargo-retaining fittings.

One advantage of the panels shown in FIGS. 11 19 is that the rectangularframe portions of the panels form shoulders which tend to keep cargoitems in the central areas of the panels. Such shoulders are indicatedby reference numeral 95 in FIGS. 11 17.

The panel cross-sectional configurations shown in FIGS. 1 V 13 areespecially suitable for reversible panels in that each of thecross-sectional configurations is symmetrical with respect to a centralplane but the asymmetrical cross sections shown in FIGS. 14 16 are alsosuitable because the panels are relatively thin.

Socket structures that may be used for reversible panels are shown inFIGS. 20 to 32 which will now be described.

In FIGS. 20 and 21 the socket comprises an aperture 96 through thethickness of the solid marginal portion of the panel in combination withtwo plates 98 at the opposite entrances of the aperture, the plate beingsecured by suitable rivets 100 that extend through the thickness of thepanel. As indicated in dotted lines in FIG. 20 the aperture 96 may beelongated to the configuratiop of a slot of suitable width and length.The socket cooperates with complementary cargo-retaining fittings in thegeneral manner disclosed in Parker US. Pat. No. 2,688,504 and Elsner US.Pat. No. 2,743,684, which prior disclosures are hereby incorporated intothe present disclosure by reference. With cargo items tied to the panelby straps or nets that are connected to the cargo-retaining fittings,the cargo items may in effect, be tied to the floor structure of theaircraft in awell known manner by locking dogs thatmake overlappingengagement with the solid margins of the panel as disclosed in thepreviously mentioned Davidson patent.

For cooperation with complementary cargo fittings the two plates 98 inFIGS. 20 and 21 are formed with identical slots 102 which are narrowerthan the 96 and register therewith. Each of the slots 102 in the twoplates is provided with a pair of enlargements 104 to receive headedstuds of the cargo fittings and each of the slots 104 is flanked bypairs of flanges 105 which are formed by narrowing the slot. The pairsof flanges 105 overhang the underlying slot 96 in the panel forengagement with the heads of the studs of the cargo fittings. Since thetwo plates 98 are identical it is apparent that each of the describedsockets may be used for engagement with cargo-retaining fittings oneither of the two faces of the reversible panel.

The apertures 96 in the solid material of a reversible panel, do, ofcourse, weaken the panel locally but the added plates 98 reinforce thepanel and actually make the panel stronger in the region of each socket.

FIG. 22 shows how the opposite surfaces of a panel may be formed withshallow recesses 106 to seat the two plates 96 respectively, so thateach of the plates is partially embedded inthe material of the panel.

FIG. 23 shows how deeper recesses 108 may be provided to seat the twoplates 98 with the two plates flush with the opposite faces of thepanel. Such a construction greatly lessens the liklihood of damage tothe socket structure.

FIG. 24 shows how a relatively thick panel may be provided with recesses110 which are substantially deeper than the thickness of the two plates98 whereby the two plates are offset inwardly from the'correspondingfaces of the panel for even protection of the sockets.

FIGS. and 26 show the simplest form of sockets for a reversible panel.Each of the sockets comprises an elongated aperture 1 12 in the materialof the solid marginal portion of the panel, the aperture being formedwith enlargements 114 on the opposite faces of the panel to receiveheaded studs of cargo-retaining fittings and the aperture being furtherprovided with overhanging flanges 115 on the opposite faces of the panelfor engagement with the heads of the studs.

FIGS. 27 29 show how a reversible panel may be provided with two sets ofrecesses on its opposite faces respectively for engagement withcargo-retaining fittings. FIG. 28 shows how one set of recesses 116 mayopen on one face of the panel and FIG. 29 shows how a second set ofrecesses 118 may open onto the opposite face of the panel. Each of therecesses 1 16 and 118 is of the general configuration heretoforedescribed with two enlargements 120 to receive the headed studs offittings and with overhanging pairs of flanges 122 to engage the headsof the studs. It will be noted that each of the sockets 116, 118 is of adepth greater than one half the thickness of the panel. I

FIGS. 32 also show how a panel may be equipped with two sets of socketsopening onto its two opposite faces respectively for engagement withcargoretaining fittings. Each socket comprises an elongated recess 124in the corresponding face of the panel in cooperation with an overlyingmetal plate 125 that is suitably anchored to the panel, for example bymeans of rivets 126. As indicated in FIG. 30 each of the recesses 124 isof elongated configuration and each of the corresponding plates 125 iscorrespondingly elongated. Each plate 125 is provided with a slot 128which registers with the corresponding recess 124 and the slot has twoenlargements 128 each of which is flanked by pairs of overhangingflanges 130 that are provided by the plate.

It is to be noted that although FIGS. 27 32 show how reversible panelsmay be provided with two sets of sockets opening onto their oppositefaces respectively, it is apparent that if a panel is not reversible itmay be provided with a single set of such sockets.

FIGS. 33 and 34 show how a socket for a panel may be formed by a metalstamping 132 that is anchored to the upper surface of the panel byrivets 134 without weakening the panel. The metal stamping 132 is offsetto form a cavity 135 which is defined in part by the panel and the metalstamping is further formed with a slot 136 of the previously describedconfiguration, that slot having enlargements 136 to receive the headedstud of a cargo-retaining fitting and having pairs of flanges 138overhanging the cavity 135 to engage the heads of the studs.

FIG. shows a panel which is similar in construction to the previouslydescribed panel shown in FIG. 14 in that the panel has a central web 140and a rectangular marginal frame portion 142 that is integral with theweb as indicated in FIG. 37. The frame portion 142 is tapered in that ithas an inclined shoulder 144 to serve as a transition to the centralweb. Frame portion 142 is formed with a suitable number of recesses orsockets 145 of the same character as the heretofore described socketsshown in FIGS. 27 and 29.

A special feature of this embodiment of the invention is that the frameportion 142 has a number of integral extensions 146 which extend towardsthe central region of the central web and are integral with the web toserve as reinforcements for the web. In this particular embodiment ofthe invention the extensions 146 are fingers that are tapered in plan.Each extension 146 is also tapered in thickness in that the transitionshoulder 144 of the frame portion continued around each extension. Thisparticular embodiment of the invention is further characterized by apair of additional extensions 148 adjacent each of the four corners ofthe panel, the additional extensions being relatively short andrelatively blunt as shown.

The extensions 146 and 148 of the frame portion 142 have the virtue ofsubstantially increasing the rigidity of the panel at the cost ofrelatively little additional material. When cargo is anchored to thepanel by a tensioned net,'the increased rigidity of the panel reducesthe upward flexure of the margins of the panel by the tension of the netand thus reduces the liklihood that the margins of the panel will beexcessively flexed to interfere with engagement by the panel with theoverhanging locks that are provided on the airplane floor. The increasedrigidity of the panel is also advantageous in making the panel morecapable of withstanding upward loads that are applied to the panel bythe cargoretaining net when the cargo tends to move upward relative tothe .airplane floor in response to abrupt downward accelerations of theairplane that sometimes occurs in flight because of adverse weatherconditions.

The panel shown in FIG. 35 need not be of one-piece construction, i.e.the extensions 146 and 148 need not be actually integral with the frameportion 142. For example, FIG. 39 which-is a sectional view like FIG. 37

shows a rectangular frame portion 142a may be integral with the centralweb 140a but the various extensions of the .frame may be riveted orotherwise bonded to the central web 140. Thus in FIG. 39 a fingerextension 146a is a separate piece of material which at its outer end isflush with the frame 142a as shown and at its inner end has the usualtransition shoulder 144a to the plane of the central web 140.

The advantages of the various described embodiments of the inventionover conventional pallets may be appreciated when it is considered thatthe service life is increased from the usual service life of one to twoyears to a longer service life of three to five years. At the same timethe'new pallet constructions provide more cargo space because of theirreduced thickness and the saving in weight. The cost of the new palletconstruction is substantially less than the cost of conventional palletsand, in addition, all of the material of the new pallet constructionsmay be salvaged at the end of the service life of the pallets.

My description in specific detail of the selected embodiments of theinvention will suggest various changes, substitutions and otherdepartures from my disclosure within the spirit and scope of theinvention.

Iclaim:

l. A pallet in the form of a rectangular panel for anchorage of cargothereon in the cargo space of an aircraft by overhanging lock means andto carry cargo to and from the cargo space by gliding over rotarysupport elements,

said panel having a rectangular marginal frame portion encompassing allof its four sides,

said frame portion being thicker than a major central portion of thepanel with the four sides of the frame portion interconnected to cause atransverse force applied to any one side of the panel toward the centralportion thereof to be transmitted to adjoining parallel sides of theframe portion for transmission to the fourth side of the frame portion,

said frame portion being equipped with means for engagement with cargosecuring means,

the major central portion of the panel being formed by a single sheet,

the frame portion being attached to the single sheet,

a part of the frame portion being of reduced thickness and overlappingthe edge of the sheet and being attached thereto in face to facerelationship, i

the edge of the sheet being tapered,

the frame portion having a groove of cross section complementary to thecross section of the tapered edge of the sheet, the groove beinginterlocked with the edge of the sheet to oppose separation of the edgelaterally away from the frame portion.

2. A pallet in the form of a rectangular panel for anchorage of cargothereon in the cargo space of an aircraft by overhanging lock means andto carry cargo to and from the cargo space by gliding over rotarysupport elements, said pallet having a major central portion formed by asingle sheet;

a rectangular marginal frame portion encompassing all four sides of saidpallet;

said frame portion attached to the said single sheet forming the centralportion of the panel;

said frame portion being substantially thicker than the major centralportion of the panel with the four sides of the frame portioninterconnected to cause a transverse force applied to any one side ofthe panel towards the central portion thereof to be transmitted toadjoining parallel sides of the frame portion for transmission to thefourth side of the frame portion,

said frame portion being recessed to receive in overlapping engagementthe edge of said sheet and attached to said sheet;

the four sides of said rectangular frame portion being formed byseparate members leading into four corners of the frame structure andattached to the sin- I gle sheet;

said four members being interlocked at the corners of said frameportion; and

means carried by said frame portion for engagement with conventionalcargo-securing means.

3. A pallet for the placing of cargo thereon and the securing of thecargo thereto for movement of the cargo over rotary elements to and fromthe cargo space of a cargo carrier and to permit the cargo to bereleasably secured in the cargo space by overhanging lock means,comprising:

a rectangular panel having a central load carrying portion and arectangular frame surrounding the central portion and united therewith,

said central load carrying portion formed of a substantiallyincompressible material of such thickness and mass to resiliently flexlocally in response to impact loads produced by cargo dropped thereonand to resiliently flex locally in response to engagement with a rotarysupport element spaced above the supporting plane of adjacent rotaryelements supporting the pallet as the same moves into and over theelevated support element to distribute a substantial portion of thecargo load carried by said central portion to supporting rotary elementsadjacent the rotary element producing the flexure whereby high unit loadstresses in the central portion and the elevated rotary element arereduced;

said frame member comprising a plurality of elements each having agreater rigidity than said central portion and each formed with a recessreceiving one marginal edge of said central portion to support andreinforce the edge received therein;

means for permanently anchoring a marginal edge of the central portionin a recess of an element of the frame member; and

means carried by said frame member for engagement with cargo-securingmeans for holding said pallet in a selected position within the cargospace of the cargo carrier.

4. A pallet as defined in claim 3 in which a face of said frame memberis substantially coplanar with a corresponding tace of said loadcarrying central portion.

5. A pallet as defined in claim 3 in which said central portion isformed of an aluminum sheet.

6. A pallet for the placing of cargo thereon and the securing of thecargo thereto for movement of the cargo over rotary elements to and fromthe cargo space of a cargo carrier and to permit the cargo to bereleasably secured in the cargo space by overhanging lock means,comprising:

a rectangular panel having a metallic sheet-like central portion and arectangular frame surrounding the central portion and united therewith,

said central portion. having high resistance to permanent deformation,being substantially incompressible and of an area and thickness toresiliently absorb impact loads and to resiliently flex in response tolocal forces produced by a rotary support element spaced above thesupporting plane of adjacent rotary elements supporting the pallet asthe-pallet moves over the elevated support element, to distribute asubstantial portion of the cargo load to supporting rotary elementsadjacent the rotary element producing the flexure of said centralportion, whereby high unit load stresses produced in the central portionby the elevated rotary element are reduced;

' said frame member being more rigid than said central portion andcomprising a plurality of elements, each formed with a recess receivingone marginal edge of said central portion,

said recess defining at least one sidewall which overlies and facewisely engages a surface of a marginal edge of said central portion;

means for permanently anchoring a marginal edge of the central portionin a recess of an element of the frame member; and

means carried by said frame member for engagement with cargo-securingmeans for holding said pallet in a selected position within the cargospace of the cargo carrier.

7. A pallet as defined in claim 6 in which said recess defines a pair ofsidewalls which engage opposite surfaces of a marginal edge of saidcentral portion.

8. A pallet as defined in claim 6 in which a face of said frame memberis substantially coplanar with a corresponding face of said centralportion.

9. A pallet as defined in claim 6 in which said central portionis formedof a single sheet of aluminum.

10. A pallet for the placing of'cargo thereon and the a rectangularsheet forming a central load carrying element of said pallet,

said sheet formed of a metal highly resistant to permanent deformationunder impact loads and of such thickness and mass to resiliently flexlocally in response to forces produced by cargo dropped thereon and toresiliently flex in response to engagement with a support element spacedabove the supporting plane of adjacent elements supporting the palletasthe same moves into and over the elevated support element to distributea substantial portion of the cargo load carried by said pallet tosupporting elements adjacent the element producing the flexure wherebyhigh unit load stresses in the sheet .and the elevated rotary elementare reduced;

a frame member comprising a plurality of elongate members, each elementbeing thicker than and having a greater rigidity than said sheet;

each of said elements being formed with a cavity receiving one marginaledge of said sheet, the cavity having a length equal to the marginaledge received therein;

means for permanently securing a marginal edge of the sheet receivedwithin a cavity of the element of 40 the frame member whereby the framemember encompasses all four sides of the sheet to reinforce the same;and

means carried by said frame member for engagement with cargo-securingmeans for holding said pallet in a selected position within the cargospace of the cargo carrier.

11. A pallet as set forth in claim 10 in which the edge of the sheet istapered and in which each elongate element has a groove of a crosssection complementary of the cross sectionof the tapered edge of thesheet that interlocks with the edge of the sheet and thereby opposingseparation of the edge of the sheet laterally away from the elongateelement.

12. A pallet for the placing of cargo thereon and the securing of thecargo thereto for movement'of the cargo over rotary elements to and fromthe cargo space of a cargo carrier and to permit the cargo to bereleasably secured in the cargo space by overhanging lock means,comprising:

a rectangular sheet of metal forming a central load carrying element ofsaid pallet, said sheet being of such thickness as to resiliently flexlocally in response to impact forces produced by cargo dropped thereonand to resiliently flex in response to engagement with a support elementof the car 0 carrier spaced above the supporting plane of a jacentelements supporting the pallet as the same moves into and over thesupport element to distribute a substantial portion of the cargo loadcarried by said pallet to supporting elements adjacent the elementproducing the flexure whereby high unit load stresses in the sheet andthe elevated totary element are reduced;

a frame member of a thickness greater than said sheet extending aboutthe four marginal edges of the same to reinforce and stiffen the edgesof the sheet,

said frame being substantially rigid and resistant to flexing stressesproduced by bending loads induced in said frame; and t 4 means carriedat spaced locations about said frame for holding said pallet in apreselected position within the cargo space of the cargo carrier andreceiving and cooperating with means carried by a load confining elementadapted to hold cargo to said pallet.

13. A pallet as defined in claim 12 in which said frame is integral withsaid sheet of metal.

UNITED STATES- PATENT- OFFICE v CERTIFICATE OF CORRECTION Patent No.2,693,677 Dated nni'n'hpr 17 1079 Invent r( ROBERT LOOKER It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

In column 14, at the end of the column the following claim is added:

"14. A pallet as set forth in Claim 2 which includes reinforcementinserts at the four corners of the frame portion, said insertsinterlocking the four members.--

Signed and sealed this 17th day of April 1973 (SEAL) Attestz' EDWARDM.FLETCHER,JR. ROBERT GOTTSCHALK Attesting Officer Commissioner ofPatents ORM PO-105O (10-69) uscoMM-Dc 60376-P69 k Hi5. GOVERNMENTPRINTING OFFICE: 1969 0-366-334

1. A pallet in the form of a rectangular panel for anchorage of cargothereon in the cargo space of an aircraft by overhanging lock means andto carry cargo to and from the cargo space by gliding over rotarysupport elements, said panel having a rectangular marginal frame portionencompassing all of its four sides, said frame portion being thickerthan a major central portion of the panel with the four sides of theframe portion interconnected to cause a transverse force applied to anyone side of the panel toward the central portion thereof to betransmitted to adjoining parallel sides of the frame portion fortransmission to the fourth side of the frame portion, said frame portionbeing equipped with means for engagement with cargo securing means, themajor central portion of the panel being formed by a single sheet, theframe portion being attached to the single sheet, a part of the frameportion being of reduced thickness and overlapping the edge of the sheetand being attached thereto in face to face relationship, the edge of thesheet being tapered, the frame portion having a groove of cross sectioncomplementary to the cross section of the tapered edge of the sheet, thegroove being interlocked with the edge of the sheet to oppose separationof the edge laterally away from the frame portion.
 2. A pallet in theform of a rectangular panel for anchorage of cargo thereon in the cargospace of an aircraft by overhanging lock means and to carry cargo to andfrom the cargo space by gliding over rotary support elements, saidpallet having a major central portion formed by a single sheet; arectangular marginal frame portion encompassing all four sides of saidpallet; said frame poRtion attached to the said single sheet forming thecentral portion of the panel; said frame portion being substantiallythicker than the major central portion of the panel with the four sidesof the frame portion interconnected to cause a transverse force appliedto any one side of the panel towards the central portion thereof to betransmitted to adjoining parallel sides of the frame portion fortransmission to the fourth side of the frame portion, said frame portionbeing recessed to receive in overlapping engagement the edge of saidsheet and attached to said sheet; the four sides of said rectangularframe portion being formed by separate members leading into four cornersof the frame structure and attached to the single sheet; said fourmembers being interlocked at the corners of said frame portion; andmeans carried by said frame portion for engagement with conventionalcargo-securing means.
 3. A pallet for the placing of cargo thereon andthe securing of the cargo thereto for movement of the cargo over rotaryelements to and from the cargo space of a cargo carrier and to permitthe cargo to be releasably secured in the cargo space by overhanginglock means, comprising: a rectangular panel having a central loadcarrying portion and a rectangular frame surrounding the central portionand united therewith, said central load carrying portion formed of asubstantially incompressible material of such thickness and mass toresiliently flex locally in response to impact loads produced by cargodropped thereon and to resiliently flex locally in response toengagement with a rotary support element spaced above the supportingplane of adjacent rotary elements supporting the pallet as the samemoves into and over the elevated support element to distribute asubstantial portion of the cargo load carried by said central portion tosupporting rotary elements adjacent the rotary element producing theflexure whereby high unit load stresses in the central portion and theelevated rotary element are reduced; said frame member comprising aplurality of elements each having a greater rigidity than said centralportion and each formed with a recess receiving one marginal edge ofsaid central portion to support and reinforce the edge received therein;means for permanently anchoring a marginal edge of the central portionin a recess of an element of the frame member; and means carried by saidframe member for engagement with cargo-securing means for holding saidpallet in a selected position within the cargo space of the cargocarrier.
 4. A pallet as defined in claim 3 in which a face of said framemember is substantially coplanar with a corresponding face of said loadcarrying central portion.
 5. A pallet as defined in claim 3 in whichsaid central portion is formed of an aluminum sheet.
 6. A pallet for theplacing of cargo thereon and the securing of the cargo thereto formovement of the cargo over rotary elements to and from the cargo spaceof a cargo carrier and to permit the cargo to be releasably secured inthe cargo space by overhanging lock means, comprising: a rectangularpanel having a metallic sheet-like central portion and a rectangularframe surrounding the central portion and united therewith, said centralportion having high resistance to permanent deformation, beingsubstantially incompressible and of an area and thickness to resilientlyabsorb impact loads and to resiliently flex in response to local forcesproduced by a rotary support element spaced above the supporting planeof adjacent rotary elements supporting the pallet as the pallet movesover the elevated support element to distribute a substantial portion ofthe cargo load to supporting rotary elements adjacent the rotary elementproducing the flexure of said central portion, whereby high unit loadstresses produced in the central portion by the elevated rotary elementare reduced; said frame member being more rigid than said centralportion and comprising a plurality of elements, each formed with arecess receiving one marginal edge of said central portion, said recessdefining at least one sidewall which overlies and face wisely engages asurface of a marginal edge of said central portion; means forpermanently anchoring a marginal edge of the central portion in a recessof an element of the frame member; and means carried by said framemember for engagement with cargo-securing means for holding said palletin a selected position within the cargo space of the cargo carrier.
 7. Apallet as defined in claim 6 in which said recess defines a pair ofsidewalls which engage opposite surfaces of a marginal edge of saidcentral portion.
 8. A pallet as defined in claim 6 in which a face ofsaid frame member is substantially coplanar with a corresponding face ofsaid central portion.
 9. A pallet as defined in claim 6 in which saidcentral portion is formed of a single sheet of aluminum.
 10. A palletfor the placing of cargo thereon and the securing of the cargo theretofor movement of the cargo over rotary elements to and from the cargospace of a cargo carrier and to permit the cargo to be releasablysecured in the cargo space by overhanging lock means, comprising: arectangular sheet forming a central load carrying element of saidpallet, said sheet formed of a metal highly resistant to permanentdeformation under impact loads and of such thickness and mass toresiliently flex locally in response to forces produced by cargo droppedthereon and to resiliently flex in response to engagement with a supportelement spaced above the supporting plane of adjacent elementssupporting the pallet as the same moves into and over the elevatedsupport element to distribute a substantial portion of the cargo loadcarried by said pallet to supporting elements adjacent the elementproducing the flexure whereby high unit load stresses in the sheet andthe elevated rotary element are reduced; a frame member comprising aplurality of elongate members, each element being thicker than andhaving a greater rigidity than said sheet; each of said elements beingformed with a cavity receiving one marginal edge of said sheet, thecavity having a length equal to the marginal edge received therein;means for permanently securing a marginal edge of the sheet receivedwithin a cavity of the element of the frame member whereby the framemember encompasses all four sides of the sheet to reinforce the same;and means carried by said frame member for engagement withcargo-securing means for holding said pallet in a selected positionwithin the cargo space of the cargo carrier.
 11. A pallet as set forthin claim 10 in which the edge of the sheet is tapered and in which eachelongate element has a groove of a cross section complementary of thecross section of the tapered edge of the sheet that interlocks with theedge of the sheet and thereby opposing separation of the edge of thesheet laterally away from the elongate element.
 12. A pallet for theplacing of cargo thereon and the securing of the cargo thereto formovement of the cargo over rotary elements to and from the cargo spaceof a cargo carrier and to permit the cargo to be releasably secured inthe cargo space by overhanging lock means, comprising: a rectangularsheet of metal forming a central load carrying element of said pallet,said sheet being of such thickness as to resiliently flex locally inresponse to impact forces produced by cargo dropped thereon and toresiliently flex in response to engagement with a support element of thecargo carrier spaced above the supporting plane of adjacent elementssupporting the pallet as the same moves into and over the supportelement to distribute a substantial portion of the cargo load carried bysaid pallet to supporting elements adjacent the element producing theflexure whereby high unit load stresses in the sheet and the elevatedrotary element are reduced; a frame member of a thickness greater thansaid sheet extending about the four marginal edges of the same toreinforce and stiffen the edges of the sheet, said frame beingsubstantially rigid and resistant to flexing stresses produced bybending loads induced in said frame; and means carried at spacedlocations about said frame for holding said pallet in a preselectedposition within the cargo space of the cargo carrier and receiving andcooperating with means carried by a load confining element adapted tohold cargo to said pallet.
 13. A pallet as defined in claim 12 in whichsaid frame is integral with said sheet of metal.